It is a general practice to print information on paper and check the information using an image forming apparatus such as an MFP (Multi Function Peripheral). A quantity of use of paper increases according to an increase in an information amount.
However, most of prints printed in this way are not required to be preserved and are temporarily recorded and discarded in a short period. Because of increasing awareness of environmental issues such as protection of forest resources, which are paper raw materials, and a reduction in carbon dioxide emission, use of reverse side paper, duplex printing, use of recycled paper, and the like are commonly performed. Further, as a method of enabling repeated use of paper, there are known a method of mechanically or chemically peeling an image forming material (e.g., a toner) on paper and a method of using an erasable toner, which is erased by heat, light, a chemical, or the like, for printing.
Printing and erasing with the erasable toner are repeated to realize protection of forest resources and a reduction in carbon dioxide emission using paper plural times. If an erasable toner, which is erased by heat, is used, in some cases, erasing temperature varies and erasing unevenness occurs because of variations in raw materials of the erasable toner. Therefore, the erasing temperature of an erasing device is often set rather high. As a result, a paper curl, the shine or gloss of an erasing mark, high-temperature offset, and the like sometimes occur. On the other hand, if the erasing temperature of the erasing device is set rather low, erasing unevenness sometimes occurs to deteriorate visibility when printing is performed next time using erased paper.